The present invention relates generally to fertilizer compositions and a method for administering the same. In particular the invention relates to phosphate fertilizer compositions including citric acid and a method of providing phosphates to plants.
Phosphate is an essential element in plant growth and is common in soil. Phosphates are classified by the percentage of phosphate that is soluble in water and citrate. The sum of the water-soluble and citrate-soluble phosphates (hereinafter referred to as soluble phosphates) is the amount available to plant roots.
Soils contain soluble and insoluble phosphates. By far the vast majority of phosphate compounds in soil are insoluble, normally in the form of brushites. Soluble phosphates may react with natural cations in the soil such as Ca+1 or Ca+2. Such phosphates become brushites and other insoluble crystalline compounds. Such insoluble phosphates are not available to plant roots. Soluble phosphates can be bio-organic complexes or simple soluble salts called orthophosphates, i.e., salts containing PO4xe2x88x923, HPO4xe2x88x922, or H2PO4xe2x88x921. The bio-organic complexes are produced from plant and animal wastes and degradation.
Fertilizers utilize orthophosphates and polyphosphates (chains of orthophosphates). However, not all of the orthophosphate is available to the plant roots. When the orthophosphate comes in contact with a strong cation in the soil, an insoluble crystal is formed such as a brushite or monetite. This problem is overcome by saturating the cation rich soil with soluble phosphates. Over saturation of orthophosphates in the soil ties up the inhibiting cations, which then allows some soluble phosphates to travel from the surface of the soil to the plant roots. However, this practice is wasteful and not environmentally sound. The excess phosphates can run off into waterways where the results can be devastating.
Chelating agents have recently been used to chelate and transport metal ions to plant roots. U.S. Pat. No. 5,372,626 discloses a method for providing metal ions consisting of Fe+3, Mn+2, Cu+2, and Zn+2 to plant roots by using citric acid to chelate the metal ions for transport through the soil. The use of humic acid as a chelating agent to produce a fertilizer containing stabilized predetermined levels of water-soluble and citric-acid soluble phosphoric contents is disclosed in U.S. Pat. No. 4,588,431.
The patents referred to herein are provided herewith in an Information Disclosure Statement in accordance with 37 CFR 1.97.
The present invention disclosed herein includes a plant fertilizer composition that includes an acid acting as a steric transport vehicle (STV) that may react with, chelate, or block any metal ions in the soil in which the plants grow during administration of the fertilizer. This reaction renders the metal ions substantially ineffective for reacting with the fertilizer components. The fertilizer is thereby shielded from interference with any metal ions in the soil and the delivery of the fertilizer to the plant roots is thereby enhanced.
The acid may be, but is not limited to, an organic acid and preferably citric acid.
The fertilizer composition may include phosphorus. This means that the fertilizer may include any phosphorus containing compound, acid, or salt thereof. Likewise, in one embodiment, the fertilizer composition may include phosphate ions and citric acid, the citric acid chelating any metal ions in the soil in which the plants grow thereby facilitating the transportation of phosphate to the plant roots.
In an alternative embodiment, the fertilizer composition may comprise metal ions, said acid reacting with said any metal ions in said soil in which the plants grow, thereby inhibiting any interference from said any metal ions in said soil in which the plants grow and enhancing delivery of the fertilizer metal ions to the plant roots.
The invention further discloses a method for providing a fertilizer to plants, comprising the steps of administering to the plants a fertilizer composition; and shielding the fertilizer from interference with any compounds including metal ions during said administration of the fertilizer to the plant thereby enhancing delivery of the fertilizer to the plants.
In one embodiment, the method comprises the steps of administering to the soil in which the plants grow, a plant soil fertilizer composition; and shielding the fertilizer from interference with any metal ions in the soil in which the plants grow during said administration of the fertilizer to the plant roots, thereby enhancing delivery of the fertilizer to the plant roots.
In an alternative embodiment of the method, the fertilizer composition may be foliarly applied, the steric transport vehicle reacting with or loosening up the foliar biochemical constituents to thereby facilitate the uptake of the fertilizer.
The present invention disclosed herein includes a plant fertilizer composition that includes an acid, acting as a steric transport vehicle (STV), whereby said acid may react with, chelate, or block any metal ions in the soil in which the plants grow during administration of the fertilizer. This reaction renders the metal ions substantially ineffective for reacting with the fertilizer components. The fertilizer is thereby shielded from interference with any metal ions in the soil and the delivery of the fertilizer to the plant roots is thereby enhanced.
The acid may be an organic acid. The organic acid may be, but is not limited to, an aliphatic acid, or an acid containing at least one carboxyl group. The organic acid is preferably citric acid.
Likewise, the acid may be, but is not limited to, phosphoric acid, phosphorous acid, an acid with a molecular weight of not more than 400, a phosphorus-containing acid with a molecular weight of not more than 300, a sulfur-containing acid, oxalic acid, and acetic acid. The sulfur-containing acid may be, but is not limited to, sulfuric acid and sulfurous acid.
The fertilizer composition may include phosphorus. This means that the fertilizer may include any phosphorus containing compound, acid, or salt thereof For example, the fertilizer may include a soluble phosphate compound which may be, but is not limited to, a polyphosphate compound and an orthophosphate compound.
Likewise, in one embodiment, the fertilizer composition may include phosphate ions and citric acid, the citric acid chelating any metal ions in the soil in which the plants grow thereby facilitating the transportation of phosphate to the plant roots. It has been experimentally determined that the molar ratio of citric acid concentration to the concentration of the phosphate ions is most preferably about 0.25 to 2.0.
In an alternative embodiment, the fertilizer composition may comprise metal ions, said acid reacting with said any metal ions in said soil in which the plants grow, thereby inhibiting any interference from said any metal ions in said soil in which the plants grow and enhancing delivery of the fertilizer metal ions to the plant roots.
The composition of the present invention may be provided as a dry particulate solid which may be administered to the soil as such or after its dissolution in water. Compositions in accordance with the present invention may also be provided in the form of an aqueous solution either ready for administration or as a concentrate which is diluted prior to use.
The invention further discloses a method for providing a fertilizer to plants, comprising the steps of administering to the plants a fertilizer composition; and shielding the fertilizer from interference with any compounds including metal ions during said administration of the fertilizer to the plant thereby enhancing delivery of the fertilizer to the plants.
The fertilizer may be administered by various means known per se. The fertilizer may be a dry particulate solid or aqueous solution as described above. In one embodiment, the method may comprise the steps of administering to the soil in which the plants grow, a plant soil fertilizer composition; and shielding the fertilizer from interference with any metal ions in the soil in which the plants grow during said administration of the fertilizer to the plant roots, thereby enhancing delivery of the fertilizer to the plant roots.
In an alternative embodiment of the method, the fertilizer composition may be foliarly applied, a steric transport vehicle (STV) reacting with or loosening up the foliar biochemical constituents to thereby facilitate the uptake of the fertilizer.
The fertilizer composition may be shielded by the use of a steric transport vehicle (STV) included in the fertilizer. The STV may use pH, steric blocking, passive cation holdup, and chelation to facilitate the transportation of the fertilizer to the plants.
In one embodiment, said fertilizer is shielded from interference with said any metal ions in said soil by chelating said any metal ions.
The STV is preferably an acid. Acids are preferred that have a network of carboxyl groups working in unison and synergistically share xcex2-hydroxyl and xcex1-hydroxyl groups. These properties foster the hold up or chelation of cations in the soil. To maxime effectiveness, it is further preferred that the STV be transported to the plants for uptake along with the fertilizer constituents, e.g., the water soluble constituents such as phosphates. Thus, acids, particularly organic acids, of small molecular weights are preferred due to their similar migration and holdup characteristics, as that of the fertilizer constituents including, e.g., phosphate compounds. The organic acid may be, but is not limited to, an aliphatic acid or an acid containing at least one carboxyl group.
The organic acid is preferably citric acid. The size to carboxyl site ratio of citric acid, combined with its sharing of xcex1 and xcex2 carbons makes citric acid particularly effective to chelate metal ions in the soil. Its multiple active sites act in unison to make light common bonds with metals. The xcex2-hydroxyl and xcex1-carboxyl groups on this tricarboxylic acid have been shown to be much more effective to hold up or chelate cations than other acids including simple organic acids, and aromatic acids. The large steric blocking properties of citric acid block out cations and shield the fertilizer constituents, e.g., the phosphates. Citric acid farther uses pH to enhance the solubility of the fertilizer constituents, e.g., phosphate compounds. The size of the citrate compound and its vastly negative sites, along with its solubility, allows it to be transported along with the fertilizer constituents, e.g., water soluble constituents such as phosphates, and further allows it to perform an interference against a cation attack.
Likewise, the acid may be, but is not limited to, phosphoric acid, phosphorous acid, an acid with a molecular weight of not more than 400, a phosphorus-containing acid with a molecular weight of not more than 300, a sulfur-containing acid, oxalic acid, and acetic acid. The sulfur-containing acid may be, but is not limited to, sulfuric acid and sulfurous acid.
The fertilizer composition may include phosphorus. This means that the fertilizer may include any phosphorus containing compound, acid, or salt thereof. For example, the fertilizer may include a soluble phosphate compound which may be, but is not limited to, a polyphosphate compound and an orthophosphate compound.
Likewise, in one embodiment of the method, the fertilizer composition may include phosphate ions and citric acid, the citric acid chelating any metal ions in the soil in which the plants grow thereby facilitating the transportation of phosphate to the plant roots. It has been experimentally determined that the molar ratio of citric acid concentration to the concentration of the phosphate ions is most preferably about 0.25 to 2.0.
In an alternative embodiment of the method, the fertilizer composition may comprise metal ions, said acid reacting with said any metal ions in said soil in which the plants grow, thereby inhibiting any interference from said any metal ions in said soil in which the plants grow and enhancing delivery of the fertilizer metal ions to the plant roots.